Noise supressor

Abstract

Provided is a method, non-transitory computer program product and system for an improved noise suppression technique for speech enhancement. It operates on speech signals from a single source such as either the output from a single microphone or the reconstructed speech signal at the receiving end of a communication application. The system performs background noise monitoring of an in-coming speech signal and determines its level, and performs a time domain gain calculation. The noise suppressed output signal is the gain shaped original speech signal.

The invention claimed is: 
     
       1. A method for improving the quality of a voice call over a communication link using a communication device, the communication device having a down-link receiver for receiving a far-end voice signal and a far-end noise signal, the method comprising the steps of:
 monitoring the noise signal to determine a noise level of a sample of the noise signal in a time domain; 
 monitoring the voice signal to determine a signal level of said sample of the voice signal in said time domain; 
 comparing said noise level to said signal level in said time domain to calculate a difference; 
 assigning a noise confidence parameter, wherein said noise confidence parameter is low when said difference is high and said noise confidence parameter is high when said difference is low; 
 calculating a gain factor, wherein said gain factor is close to 0 when said noise confidence parameter is above a first predetermined threshold and said gain factor is close to 1 when said noise confidence parameter is below a second predetermined threshold and said gain factor increases between 0 and 1 as said noise confidence parameter decreases between said first and second predetermined thresholds; and 
 applying said gain factor to said voice signal to produce an enhanced speech signal; and 
 outputting said enhanced speech signal. 
 
     
     
       2. A non-transitory computer program product comprising a non-transitory computer useable medium having computer program logic stored therein, said computer program logic for enabling a computer processing device to improve the quality of a voice call over a communication link using a communication device, the communication device having a down-link receiver for receiving a far-end voice signal and a far-end noise signal, the computer program product comprising:
 code for monitoring the noise signal to determine a noise level of a sample of the noise signal in a time domain; 
 code for monitoring the voice signal to determine a signal level of said sample of the voice signal in said time domain; 
 code for comparing said noise level to said signal level in said time domain to calculate a difference; 
 code for assigning a noise confidence parameter, wherein said noise confidence parameter is low when said difference is high and said noise confidence parameter is high when said difference is low; 
 code for calculating a gain factor, wherein said gain factor is close to 0 when said noise confidence parameter is above a first predetermined threshold and said gain factor is close to 1 when said noise confidence parameter is below a second predetermined threshold and said gain factor increases between 0 and 1 as said noise confidence parameter decreases between said first and second predetermined thresholds; and 
 code for applying said gain factor to said voice signal to produce an enhanced speech signal; and 
 code for outputting said enhanced speech signal. 
 
     
     
       3. A noise suppressor for improving the audio quality of a voice call in a in a communication device comprising:
 a down-link receiver capable of receiving a noise signal and a voice signal; 
 a noise-level module for determining a noise level of a sample of said noise signal in a time domain; 
 a voice-level module for determining a voice level of said sample of said voice signal in said time domain; 
 a comparator for comparing said noise level to said signal level to calculate a difference; 
 a confidence parameter module for assigning a noise confidence parameter based on said comparator, wherein said noise confidence parameter is low when said difference is high and said noise confidence parameter is high when said difference is low; 
 a gain-factor calculator for calculating a gain factor, wherein said gain factor is close to 0 when said noise confidence parameter is above a first predetermined threshold and said gain factor is close to 1 when said noise confidence parameter is below a second predetermined threshold and said gain factor increases between 0 and 1 as said noise confidence parameter decreases between said first and second predetermined thresholds; 
 a multiplier for multiplying said gain factor with said voice signal to produce an enhanced speech signal; and 
 an output device capable of outputting said enhanced speech signal for playback to a user.